A fisheye lens distorts images. It results in images having barrel distortions. In a fisheye lens, a straight line can appear curved. But some flat-Earthers don’t realize that the opposite is also true, a fisheye lens can easily make a curved line look straight.
The salinity of seawater does not correlate to tides. Just because seawater has a higher salinity than lake water, it doesn’t mean salinity causes tide.
Some flat-Earthers claim tides are caused by salinity. They are wrong. There are bodies of water that do not have tides as large as seawater, but their salinity is much higher than seawater.
Contextualism is treating what we know as context-sensitive. We can use the epistemic contextualism as a philosophical tool to explain the Earth is spherical, and bypass all the scientific explanations.
Flat-Earthers love to shift the context to where we would no longer function as a normal human being because only in this context, most of us cannot possibly know the shape of the Earth.
But in the context where we all act like normal human beings, there’s no problem to know the Earth is spherical, even if we don’t know all the scientific details.
Atmospheric refraction causes a distant object to appear higher than its actual position. As a result, the object can be physically behind Earth’s curvature but is still visible because the light coming from it is refracted by the atmosphere.
There are many curvature calculators and simulation tools that don’t account for refraction. They would give us the correct results indicating the object’s physical positions but fail to show us the correct apparent position of the object when visually observed.
Flat-Earthers are often too happy with the calculator showing them the results they want to see and fail to see the reason for the discrepancy.
A satellite can be placed in an orbit 35786 km above Earth’s surface, and the satellite will be in motion at the same speed as the rotation of the Earth. As a result, the satellite will appear practically motionless when observed from the surface. Many communication satellites are placed in this orbit, and a satellite dish receiving signals from the satellite doesn’t have to track the satellite.
Flat-Earthers often take the fact that satellites are in motion and most satellite dishes have a fixed direction as ‘proof’ there’s something suspicious about satellites. They are wrong.
These days, predicting eclipses is easily done using computers. Prediction is made by determining the position of the Sun and the Moon at a time, and calculating if an eclipse happens. The same procedure is then repeated numerous time, each for a different time.
The victims of the flat-Earth dogma insist nobody can predict eclipses from the position of the Sun and the Moon. They believe NASA simply used the Saros cycle to predict eclipses by calculating the interval between eclipses. They are wrong.
Proper motion is the apparent motion of stars, caused by the movement of the stars themselves, relative to the solar system. Stars will appear to shift over time, relative to other, more distant stars.
Flat-Earthers assume stars are only in motion around Polaris, or the north celestial pole. They are wrong. Stars have other apparent motions, one of which is proper motion.
In many pictures taken from space, stars are not visible, even with a dark sky. The reason is that stars are very dim compared to the primary object in the pictures. If the camera is set to take a correctly exposed image of an object that is much brighter than the stars, then the stars would not be visible in the picture. The same thing would happen everywhere, in space, or on the surface of the Earth.
Flat-Earthers often take the lack of stars as fakery. They are wrong. This is simply a limitation of any camera.
An ice shelf is a thick floating platform of ice. Ice shelves are found not only in Antarctica but also in Greenland, Canada, and Russia in the north polar region.
Flat-Earthers often show off pictures of an ice shelf as ‘proof’ of the existence of the mythical giant ice wall surrounding the Earth. They are wrong.
Long before GPS, navigators used a device called ‘sextant’ to determine the angle of a celestial body. From that data, the latitude of their current location can be determined.
This can only happen if the Earth is spherical.